The present invention relates to handles for operating electrical switching apparatus that is housed in an enclosure.
Apparatus for switching electricity is typically placed in a protective enclosure so that the operator is not exposed to a shock hazard. The apparatus is operated by a handle which is mounted on the door or other portion of the enclosure. One type of such handle is shown in U.S. Pat. No. 3,657,497. The handle also provides a means for locking it in either the on or off position.
In addition to operating the switching apparatus, the handle often interlocks the enclosure door so that it cannot be opened when the switching apparatus is in the on position. Some previous handles provided a way to defeat the interlock by using a tool.
Depending upon the type of electrical device or circuit being controlled by the switching apparatus, different functions may have to be incorporated in the handle. For example, the handle may have to be capable of being locked in only the off position, or both the on and off positions. Furthermore, it may be desirable to allow the interlock feature to be defeated so that the cabinet can be opened when the handle is in the on position. In certain applications this interlock defeating capability should be disabled when the handle is locked in the on position.
Heretofore, different models of handles incorporated different combinations of these functions. A specific model had to be selected depending upon the nature of the application. After installation of the handle, if the device or circuit controlled by its switching apparatus changed, the functions of the handle could not be altered without its total replacement. It is therefore desirable to provide a common type of handle which can be easily modified to enable different combinations of these functions.